Biological fluids, such as blood, bone marrow aspirate, and the like, are often subject to centrifuge so as to separate them by density into their separate components. For example, blood, when centrifuged, will separate into red blood cell components (denser) and a plasma component (less dense) with a small percentage of buffy coat between. Bone marrow aspirate, when centrifuged, will typically separate into a red blood cell (platelet) component, a plasma component, and a buffy coat component comprising stem cells or undifferentiated cells.